View LTC4077_4888798.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

LTC4077 Dual Input Standalone Li-Ion Battery Charger FEATURES

DESCRIPTIO

Charges Single-Cell Li-Ion Batteries from Wall Adapter and USB Inputs Automatic Input Power Detection and Selection Charge Current Programmable up to 950mA from Wall Adapter Input C/10 Charge Current Termination Thermal Regulation Maximizes Charge Rate Without Risk of Overheating* Preset Charge Voltage with 0.6% Accuracy 18A USB Suspend Current in Shutdown Power Present Status Output Charge Status Output Automatic Recharge Available in a Thermally Enhanced, Low Profile (0.75mm) 10-Lead (3mm x 3mm) DFN Package
The LTC(R)4077 is a standalone linear charger that is capable of charging a single-cell Li-Ion battery from both wall adapter and USB inputs. The charger can detect power at the inputs and automatically select the appropriate power source for charging. No external sense resistor or blocking diode is required for charging due to the internal MOSFET architecture. Internal thermal feedback regulates the battery charge current to maintain a constant die temperature during high power operation or high ambient temperature conditions. The float voltage is fixed at 4.2V and the charge current is programmed with an external resistor. The LTC4077 terminates the charge cycle when the charge current drops below the termination threshold after the final float voltage is reached. The LTC4077 can be put into shutdown mode reducing the DCIN supply current to 20A, the USBIN supply current to 10A, and the battery drain current to less than 2A even with power applied to both inputs. Other features include automatic recharge, undervoltage lockout, charge status output, power present status output to indicate the presence of wall adapter or USB power and high power/low power adjustable mode for USB compatible applications.
, LTC and LT are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. *Protected by U.S. patents, including 6522118
APPLICATIO S

Cellular Telephones Handheld Computers Portable MP3 Players Digital Cameras
TYPICAL APPLICATIO
Complete Charge Cycle (1100mAh Battery) Dual Input Battery Charger for Single-Cell Li-Ion
800mA (WALL) 500mA (USB) BAT HPWR 1000 800 600 400 200 0 4.2 4.0 3.8 3.6 3.4 5.0 2.5 0 0 0.5 1.0 2.0 1.5 TIME (HR) 2.5 3.0
4077f
WALL ADAPTER USB PORT 1mF 1mF
LTC4077 DCIN USBIN IUSB IUSBL GND
BATTERY CHARGE VOLTAGE (V) CURRENT (mA)
+
2k 1%
4077 TA01
DCIN VOLTAGE (V)
2k IDC 1% 1.24k 1%
4.2V SINGLE CELL Li-Ion BATTERY
U
CONSTANT VOLTAGE USBIN = 5V TA = 25C RIDC = 1.24k RIUSB = 2k HPWR = 5V
"%% 6)>
U
U
1
LTC4077 ABSOLUTE
(Notes 1, 9)
AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
TOP VIEW USBIN IUSB IUSBL PWR CHRG 1 2 3 4 5 11 10 DCIN 9 BAT 8 IDC 7 HPWR 6 EN
Input Supply Voltage (DCIN, USBIN) ......... -0.3V to 10V EN, CHRG, PWR, HPWR ............................ -0.3V to 10V BAT, IDC, IUSB, IUSBL ................................. -0.3V to 7V DCIN Pin Current (Note 6) ..........................................1A USBIN Pin Current (Note 6) .................................700mA BAT Pin Current (Note 6) ............................................1A BAT Short-Circuit Duration............................Continuous Maximum Junction Temperature .......................... 125C Operating Temperature Range (Note 2) .. -40C to 85C Storage Temperature Range.................. -65C to 125C
DD PACKAGE 10-LEAD (3mm 3mm) PLASTIC DFN TJMAX = 125C, JA = 40C/W (NOTE 3) EXPOSED PAD (PIN 11) IS GND, MUST BE SOLDERED TO PCB
ORDER PART NUMBER LTC4077EDD
DD PART MARKING LBWD
Order Options Tape and Reel: Add #TR Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF Lead Free Part Marking: http://www.linear.com/leadfree/ Consult LTC Marketing for parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
SYMBOL VDCIN VUSBIN IDCIN PARAMETER Supply Voltage Supply Voltage DCIN Supply Current
The denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VDCIN = 5V, VUSBIN = 5V, HPWR = 5V unless otherwise noted.
CONDITIONS

MIN 4.3 4.3
TYP
MAX 8 8 700 100 40 700 100 36 20 4.225 4.242 840 500 108 56 -6 -2 2 1.05 1.05 0.22 0.11 0.11
UNITS V V A A A A A A A V V mA mA mA mA A A A V V V mA/mA mA/mA
Charge Mode (Note 4), RIDC = 10k Standby Mode; Charge Terminated Shutdown Mode (EN = 5V) Charge Mode (Note 5), RIUSB = RIUSBL = 10k, VDCIN = 0V Standby Mode; Charge Terminated, VDCIN = 0V Shutdown (VDCIN = 0V, EN = 5V) VDCIN > VUSBIN IBAT = 1mA (Note 9) IBAT = 1mA, 0C < TA < 85C, 4.3V < VCC < 8V RIDC = 1.25k, Constant-Current Mode RIUSB = 2.1k, Constant-Current Mode RIDC = 10k or RIUSB = 10k RIUSBL = 4k, HPWR = 0 Standby Mode, Charge Terminated Shutdown Mode (Charger Disabled) Sleep Mode (VDCIN = 0V, VUSBIN = 0V) Constant-Current Mode Constant-Current Mode Constant-Current Mode VDCIN = 5V, RIDC = 1.25k (Note 7) VUSBIN = 5V, VDCIN = 0V

150 50 20 150 50 18 10 4.2 4.2 800 476 100 50 -3 -1 1 1 1 0.2 0.1 0.1
IUSBIN
USBIN Supply Current

VFLOAT IBAT
Regulated Output (Float) Voltage BAT Pin Current

4.175 4.158 760 450 92 44
VIDC VIUSB VIUSBL IC/IO
IDC Pin Regulated Voltage IUSB Pin Regulated Voltage IUSBL Pin Regulated Voltage Charge Current Termination Threshold
0.95 0.95 0.18

0.09 0.09
2
U
4077f
W
U
U
WW
W
LTC4077 ELECTRICAL CHARACTERISTICS
SYMBOL IC/2 ITRIKL PARAMETER Charge Current Termination Threshold Trickle Charge Current
The denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VDCIN = 5V, VUSBIN = 5V unless otherwise noted.
CONDITIONS HPWR = 0V (Note 8) VBAT < VTRIKL; RIDC = 1.25k VBAT < VTRIKL; RIUSB = 2.1k VBAT < VTRIKL; RIUSBL = 4k VBAT Rising Hysteresis From Low to High Hysteresis From Low to High Hysteresis VDCIN from Low to High, VBAT = 4.2V VDCIN from High to Low, VBAT = 4.2V VUSBIN from Low to High VUSBIN from High to Low

MIN 0.45 60 30 17 2.8 4 3.8 140 20 140 20 0.4 1 0.4 1
TYP 0.5 80 47.5 25 2.9 100 4.15 200 3.95 200 180 50 180 50 0.7 2 0.7 2 0.35 0.35 100 6 1.5 250 400 550 105
MAX 0.55 100 65 33 3 4.3 4.1 220 80 220 80 1 5 1 5 0.6 0.6 135 10 2.2 325
UNITS mA/mA mA mA mA V mV V mV V mV mV mV mV mV V M V M V V mV ms ms s m m C
VTRIKL VUVDC VUVUSB VASD-DC VASD-USB VEN REN VHPWR RHPWR VCHRG VPWR VRECHRG tRECHRG tTERMINATE tSS RON-DC RON-USB TLIM
Trickle Charge Threshold Voltage DCIN Undervoltage Lockout Voltage USBIN Undervoltage Lockout Voltage VDCIN - VBAT Lockout Threshold VUSBIN - VBAT Lockout Threshold EN Input Threshold Voltage EN Pulldown Resistance HPWR Input Threshold Voltage HPWR Pulldown Resistance CHRG Output Low Voltage PWR Output Low Voltage Recharge Battery Threshold Voltage Recharge Comparator Filter Time Termination Comparator Filter Time Soft-Start Time Power FET "ON" Resistance (Between DCIN and BAT) Power FET "ON" Resistance (Between USBIN and BAT) Junction Temperature in Constant-Temperature Mode
ICHRG = 5mA IPWR = 5mA VFLOAT - VRECHRG, 0C < TA < 85C VBAT from High to Low IBAT Drops Below Termination Threshold IBAT = 0 to Full-Scale
65 3 0.8 175
Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: The LTC4077E is guaranteed to meet the performance specifications from 0C to 70C. Specifications over the -40C to 85C operating temperature range are assured by design, characterization and correlation with statistical process controls. Note 3: Failure to correctly solder the exposed backside of the package to the PC board will result in a thermal resistance much higher than 40C/W. See Thermal Considerations. Note 4: Supply current includes IDC pin current (approximately 100A) but does not include any current delivered to the battery through the BAT pin.
Note 5: Supply current includes IUSB and IUSBL pin currents (approximately 100A each) but does not include any current delivered to the battery through the BAT pin. Note 6: Guaranteed by long term current density limitations. Note 7: IC/10 is expressed as a fraction of measured full charge current. Note 8: IC/2 is expressed as a fraction of measured full charge current. Note 9: VCC is greater of DCIN or USBIN
4077f
3
LTC4077 TYPICAL PERFOR A CE CHARACTERISTICS
Regulated Output (Float) Voltage vs Charge Current
4.26 4.24 4.22 VFLOAT (V) VFLOAT (V) 4.20 4.18 4.16 4.14 4.12 4.10 0 100 200 300 400 500 600 700 800 CHARGE CURRENT (mA)
4077 G01
VDCIN = VUSBIN = 5V
4.200 4.195 4.190 4.185 4.180 -50 -25 0 25 50 TEMPERATURE (C) 75 100
4077 G02
VIDC (V)
RIDC = RIUSB = 2k
RIDC = 1.25k
IUSB Pin Voltage vs Temperature (Constant-Current Mode)
1.008 1.006 1.004 VIUSBL (V) VIUSB (V) 1.002 VUSBIN = 8V 1.000 0.998 0.996 0.994 0.992 -50 -25 0 25 50 TEMPERATURE (C) 75 100
4077 G04
HPWR = 5V
IBAT (mA)
VUSBIN = 4.3V
Charge Current vs IUSB Pin Voltage
900 800 700 600 IBAT (mA) IBAT (mA) 500 400 300 200 100 0 0 0.2 0.4 0.6 0.8 VIUSB (V) 1.0 1.2
4077 G06
VUSBIN = 5V HPWR = 5V RIUSB = 1.25k 200
150 RIUSBL = 2k9 100 RIUSBL = 4k9
IPWR (mA)
RIUSB = 2k
RIUSB = 10k
4
UW
Regulated Output (Float) Voltage vs Temperature
4.220 4.215 4.210 4.205 VDCIN = VUSBIN = 5V 1.008 1.006 1.004 1.002 1.000 0.998 0.996 0.994
IDC Pin Voltage vs Temperature (Constant-Current Mode)
VDCIN = 8V VDCIN = 4.3V
0.992 -50
-25
0 25 50 TEMPERATURE (C)
75
100
4077 G03
IUSBL Pin Voltage vs Temperature (Constant-Current Mode)
0.208 0.206 0.204 0.202 0.200 0.198 0.196 0.194 0.192 -50 -25 50 25 TEMPERATURE (C) 0 75 100
4077 G24
Charge Current vs IDC Pin Voltage
900 800 700 600 RIDC = 2k VDCIN = 5V RIDC = 1.25k
HPWR = 0V
VUSBIN = 8V VUSBIN = 4.3V
500 400 300 200 100 0 0 0.2 0.4 0.6 0.8 VIDC (V)
RIDC = 10k
1.0
1.2
4077 G05
Charge Current vs IUSBL Pin Voltage
250 35 VUSBIN = 5V HPWR = 0V RIUSBL = 1k9 30 25 20 15 10 5 0 0 50 150 100 VIUSBL (mV) 200 250
4077 G25
PWR Pin I-V Curve
VDCIN = VUSBIN = 5V TA = - 40C TA = 25C TA = 90C
50
0
0
1
2
4 3 VPWR (V)
5
6
7
4077 G07
4077f
LTC4077 TYPICAL PERFOR A CE CHARACTERISTICS
CHRG Pin I-V Curve
35 VDCIN = VUSBIN = 5V 30 25 ICHRG (mA) 20 15 10 200 5 0 0 1 2 4 3 VCHRG (V) 5 6 7
4077 G08
IBAT (mA)
IBAT (mA)
Charge Current vs Battery Voltage
1000 550 500
800 RDS(ON) (m)
IBAT (mA)
600
RDS(ON) (m)
400
200
VDCIN = VUSBIN = 5V JA = 40C/W RIDC = 1.25k 2.4 2.7 3.0 3.3 3.6 VBAT (V) 3.9 4.2 4.5
0
EN Pin Threshold (Rising) vs Temperature
900 VDCIN = VUSBIN = 5V 850 800 VHPWR (mV) VEN (mV) 750 700 650 600 -50 850 800 900
IDCIN (A)
-25
50 25 0 TEMPERATURE (C)
UW
TA = -40C TA = 25C TA = 90C
4077 G11
Charge Current vs Ambient Temperature
1000 ONSET OF THERMAL REGULATION 800 RIDC = 1.25k 700 600 RIDC = RIUSB = 2k 600 500 HPWR = 5V VDCIN = VUSBIN = 5V VBAT = 4V JA = 40C/W 50 25 75 0 TEMPERATURE (C) 100 125 400 900 800
Charge Current vs Supply Voltage
ONSET OF THERMAL REGULATION
400
RIDC = 1.25k VBAT = 4V JA = 35C/W 5.0 5.5 6.0 6.5 VDCIN (V) 7.0 7.5 8.0
0 -50 -25
300 4.0 4.5
4077 G09
4077 G10
DCIN Power FET "On" Resistance vs Temperature
VBAT = 4V IBAT = 200mA 800 750 700 450 400 350 300 250 -50 -25 650 600 550 500 450 400 50 25 75 0 TEMPERATURE (C) 100 125
USBIN Power FET "On" Resistance vs Temperature
VBAT = 4V IBAT = 200mA HPWR = 5V
350 -50 -25
50 25 75 0 TEMPERATURE (C)
100
125
4077 G12
4077 G13
HPWR Pin Threshold (Rising) vs Temperature
50 VDCIN = VUSBIN = 5V 45 40 35 30 25 20 15 10 5
DCIN Shutdown Current vs Temperature
VDCIN = 8V
750 700 650 600 -50
VDCIN = 5V
VDCIN = 4.3V
EN = 5V -25 50 25 0 TEMPERATURE (C) 75 100
4077 G16
75
100
4077 G14
-25
50 25 0 TEMPERATURE (C)
75
100
0 -50
4077 G15
4077f
5
LTC4077 TYPICAL PERFOR A CE CHARACTERISTICS
USBIN Shutdown Current vs Temperature
45 40 2.6 35 RHPWR (M) 50 25 0 TEMPERATURE (C) 100 30 IUSBIN (A) 25 20 15 10 5 0 -50 -25 50 25 0 TEMPERATURE (C) VUSBIN = 4.3V 1.8 EN = 5V 75 100 1.6 -50 -25 75 1.6 -50 -25 50 25 0 TEMPERATURE (C) 75 100
4077 G19
VUSBIN = 8V 2.4 REN (M) 2.2 2.0 2.4 2.2 2.0 1.8
VUSBIN = 5V
Undervoltage Lockout Threshold vs Temperature
4.30 4.25 DCIN UVLO 4.20 VRECHRG (V) 4.15 VUV (V) 4.10 4.05 USBIN UVLO 4.00 3.95 3.90 -50 -25 0 25 50 TEMPERATURE (C) 75 100
4077 G20
Battery Drain Current vs Temperature
5 4 3 IBAT (A) 2 1 0 -1 -50 EN 5V/DIV VBAT = 4.2V VDCIN, VUSBIN (OPEN) IBAT 500mA/DIV
-25
0 25 50 TEMPERATURE (C)
6
UW
4077 G17
EN Pin Pulldown Resistance vs Temperature
2.8 2.8 2.6
HPWR Pin Pulldown Resistance vs Temperature
4077 G18
Recharge Threshold vs Temperature
4.16 4.14 4.12 4.10 4.08 4.06 4.04 -50 VDCIN = VUSBIN = 4.3V VDCIN = VUSBIN = 8V
-25
0 25 50 TEMPERATURE (C)
75
100
4077 G21
Charge Current at Turn-On and Turn-Off
75
100
4077 G22
VDCIN = 5V RIDC = 1.25k
100ms/DIV
4077 G23
4077f
LTC4077 PI FU CTIO S
USBIN (Pin 1): USB Input Supply Pin. Provides power to the battery charger. The maximum supply current is 650mA. This pin should be bypassed with a 1F capacitor. IUSB (Pin 2): Charge Current Program for High USB Power. The charge current is set by connecting a resistor, RIUSB, to ground. When charging in constant-current mode, this pin servos to 1V. The voltage on this pin can be used to measure the battery current delivered from the USB input using the following formula: IBAT = VIUSB * 1000 RIUSB EN (Pin 6): Charge Enable Input. A logic low on this pin enables the charger. If left floating, an internal 2M pulldown resistor defaults the LTC4077 to charge mode. Pull this pin high for shutdown. HPWR (Pin 7): HPWR Enable Input. Used to control the amount of current drawn from the USB port. A logic high on the HPWR pin sets the current limit at the current programmed by the IUSB pin. A logic low on the HPWR pin sets the current limit at the current programmed by the IUSBL pin. An internal 2M pull-down resistor defaults the HPWR pin to its low current state. IDC (Pin 8): Charge Current Program for Wall Adapter Power. The charge current is set by connecting a resistor, RIDC, to ground. When charging in constant-current mode, this pin servos to 1V. The voltage on this pin can be used to measure the battery current delivered from the DC input using the following formula: IBAT = VIDC * 1000 RIDC
IUSBL (Pin 3): Charge Current Program for Low USB Power. The charge current is set by connecting a resistor, RIUSBL, to ground. When charging in constant current mode, this pin servos to 0.2V. The voltage on this pin can be used to measure the battery current delivered from the USB input using the following formula: IBAT = VIUSBL * 200 RIUSBL
PWR (Pin 4): Open-Drain Power Supply Status Output. When the DCIN or USBIN pin voltage is sufficient to begin charging (i.e. when the supply is greater than the undervoltage lockout threshold and at least 180mV above the battery terminal), the PWR pin is pulled low by an internal N-channel MOSFET. Otherwise PWR is high impedance. This output is capable of sinking up to 10mA, making it suitable for driving an LED. CHRG (Pin 5): Open-Drain Charge Status Output. When the LTC4077 is charging, the CHRG pin is pulled low by an internal N-channel MOSFET. When the charge cycle is completed, CHRG becomes high impedance. This output is capable of sinking up to 10mA, making it suitable for driving an LED.
U
U
U
BAT (Pin 9): Charger Output. This pin provides charge current to the battery and regulates the final float voltage to 4.2V. DCIN (Pin 10): Wall Adapter Input Supply Pin. Provides power to the battery charger. The maximum supply current is 950mA. This should be bypassed with a 1F capacitor. Exposed Pad (Pin 11): GND. The exposed backside of the package is ground and must be soldered to PC board ground for electrical connection and maximum heat transfer.
4077f
7
LTC4077 BLOCK DIAGRA W
DCIN 10 BAT 9 USBIN 1 CC/CV REGULATOR HPWR 7 RHPWR CC/CV REGULATOR
+
4.15V
+
DC SOFT-START DCIN UVLO USB SOFT-START USBIN UVLO
-
-
3.95V
PWR
4
10mA MAX
+
BAT CHRG 5 10mA MAX
+ -
BAT
-
+
RECHARGE LOGIC RECHRG
4.1V
-
BAT DC_ENABLE USB_ENABLE
TRICKLE TERM TRICKLE CHARGE
EN
6 REN
TERMINATION
8
-
2.9V
+ -
TDIE
CHARGER CONTROL 105C THERMAL REGULATION 100mV IBAT/1000 IBAT/1000 IBAT/200 IDC IUSB IUSBL GND 11 8 RIDC IDC 2 RIUSB IUSB 3 RIUSBL IUSBL
4077 BD
+ + -
4077f
LTC4077 OPERATIO
The LTC4077 is designed to efficiently manage charging of a single-cell lithium-ion battery from two separate power sources: a wall adapter and USB power bus. Using the constant-current/constant-voltage algorithm, the charger can deliver up to 950mA of charge current from the wall adapter supply or up to 650mA of charge current from the USB supply with a final float voltage accuracy of 0.6%. The LTC4077 has two internal P-channel power MOSFETs and thermal regulation circuitry. No blocking diodes or external sense resistors are required. Power Source Selection The LTC4077 can charge a battery from either the wall adapter input or the USB port input. The LTC4077 automatically senses the presence of voltage at each input. If both power sources are present, the LTC4077 defaults to the wall adapter source provided sufficient power is present at the DCIN input. "Sufficient power" is defined as: * Supply voltage is greater than the UVLO threshold. * Supply voltage is greater than the battery voltage by 50mV (180mV rising, 50mV falling). The open drain power status output (PWR) indicates that sufficient power is available. Table 1 describes the behavior of this status output.
Table 1. Power Source Selection
VUSBIN > 3.95V and VUSBIN > BAT + 50mV VDCIN > 4.15V and VDCIN > BAT + 50mV Device powered from wall adapter source; USBIN current < 25A PWR: LOW Device powered from USB source; PWR: LOW VUSBIN < 3.95V or VUSBIN < BAT + 50mV Device powered from wall adapter source PWR: LOW No charging PWR: Hi-Z
VDCIN < 4.15V or VDCIN < BAT + 50mV
U
Programming and Monitoring Charge Current The charge current delivered to the battery from the wall adapter supply is programmed using a single resistor from the IDC pin to ground. Likewise, the charge current from the USB supply is programmed using a single resistor from the IUSB pin to ground if HPWR is set on its high logic state or from the IUSBL pin to ground if HPWR is set on its low logic state or it is left floating. The program resistor and the charge current (ICHRG) are calculated using the following equations: RIDC = 1000 V ICHRG(DC) , ICHRG(DC) = 1000 V RIDC 1000 V RIUSB 200 V RIUSBL RIUSB = 1000 V ICHRG(USB) 200 V ICHRG(USB) , ICHRG(USB) = RIUSBL = , ICHRG(USB) = Charge current out of the BAT pin can be determined at any time by monitoring the IDC or IUSB pin voltage and using the following equations:
V IBAT = IDC * 1000, (ch arging from wall adapter) RIDC V l IBAT = IUSB * 1000, (charging from USB supply, RIUSB HPWR = high) V IBAT = IUSBL * 200, (charging from USB supply, RIUSBL HPWR = low)
4077f
9
LTC4077 OPERATIO
Programming Charge Termination The charge cycle terminates when the voltage at the IUSB, IUSBL and IDC pins falls below 100mV. For wall adapter or high power USB use the charge termination is set to 1/10th of the programmed charge current. For low power USB use (HPWR = 0V) the charge termination is set to 1/2 of the programmed charge current. The termination condition is detected by using an internal filtered comparator to monitor the IDC, IUSB and IUSBL pin voltages. When one of these voltages drops below 100mV* for longer than tTERMINATE (typically 1.5ms), the charge cycle terminates, charge current latches off and the LTC4077 enters standby mode. When charging, transient loads on the BAT pin can cause the active charge current program pin to fall below 100mV for short periods of time before the steady-state charge current has dropped below the programmed termination current. The 1.5ms filter time (tTERMINATE) on the termination comparator ensures that transient loads of this nature do not result in premature charge cycle termination. Once the average charge current drops below the termination threshold, the LTC4077 terminates the charge cycle and ceases to provide any current out of the BAT pin. In this state, any load on the BAT pin must be supplied by the battery. Low-Battery Charge Conditioning (Trickle Charge) This feature ensures that deeply discharged batteries are gradually charged before reapplying full charge current. If the BAT pin voltage is below 2.9V, the LTC4077 supplies 1/10th of the full charge current to the battery, when HPWR = high or 1/2 of the full charge current (programmed by RIUSBL) to the battery when HPWR = low, until the BAT pin rises above 2.9V. For example, if the charger is programmed to charge at 800mA from the wall adapter input and 500mA from the USB input when HPWR is high or 50mA if HPWR is low, the charge current during trickle charge mode would be 80mA, 50mA and 25mA respectively.
10
U
Automatic Recharge In standby mode, the charger sits idle and monitors the battery voltage using a comparator with a 6ms filter time (tRECHRG). A charge cycle automatically restarts when the battery voltage falls below 4.1V (which corresponds to approximately 80%-90% battery capacity). This ensures that the battery is kept at, or near, a fully charged condition and eliminates the need for periodic charge cycle initiations. If the battery is removed from the charger, a sawtooth waveform of approximately 100mV appears at the battery output. This is caused by the repeated cycling between termination and recharge events. This cycling results in pulsing at the CHRG output; an LED connected to this pin will exhibit a blinking pattern, indicating to the user that a battery is not present. The frequency of the sawtooth is dependent on the amount of output capacitance. Manual Shutdown The EN pin has a 2M pulldown resistor to GND. A logic low enables the charger and logic high disables it (the pulldown defaults the charger to the charging state). The DCIN input draws 20A when the charger is in shutdown. The USBIN input draws 18A during shutdown if no power is applied to DCIN, but draws only 10A when VDCIN > VUSBIN. Charge Current Soft-Start and Soft-Stop The LTC4077 includes a soft-start circuit to minimize the inrush current at the start of a charge cycle. When a charge cycle is initiated, the charge current ramps from zero to full-scale current over a period of 250s. Likewise, internal circuitry slowly ramps the charge current from full-scale to zero in a period of approximately 30s when the charger shuts down or self terminates. This minimizes the transient current load on the power supply during start-up and shut-off.
*Any external sources that hold the pin above 100mV will prevent the LTC4077 from terminating a charge cycle.
4077f
LTC4077 OPERATIO
Status Indicators The charge status output (CHRG) has two states: pull-down and high impedance. The pull-down state indicates that the LTC4077 is in a charge cycle. Once the charge cycle has terminated or the LTC4077 is disabled, the pin state becomes high impedance. The pull-down state is capable of sinking up to 10mA.
BAT < 2.9V
2.9V < BAT
BAT < 4.1V
EN DRIVEN LOW
U
The power supply status output (PWR) has two states: pull-down and high impedance. The pull-down state indicates that power is present at either DCIN or USBIN. If no power is applied at either pin, the PWR pin is high impedance, indicating that the LTC4077 lacks sufficient power to charge the battery. The pull-down state is capable of sinking up to 10mA.
STARTUP DCIN POWER APPLIED POWER SELECTION DCIN POWER REMOVED TRICKLE CHARGE MODE 1/10th FULL CURRENT CHRG STATE: PULLDOWN BAT > 2.9V CHARGE MODE FULL CURRENT CHRG STATE: PULLDOWN IBAT < ITERMINATE IN VOLTAGE MODE STANDBY MODE NO CHARGE CURRENT CHRG STATE: Hi-Z USBIN POWER REMOVED OR DCIN POWER APPLIED ONLY USB POWER APPLIED TRICKLE CHARGE MODE 1/2 OR 1/10th FULL CURRENT CHRG STATE: PULLDOWN BAT > 2.9V CHARGE MODE FULL CURRENT CHRG STATE: PULLDOWN IBAT < ITERMINATE IN VOLTAGE MODE STANDBY MODE NO CHARGE CURRENT CHRG STATE: Hi-Z BAT < 4.1V 2.9V < BAT BAT < 2.9V SHUTDOWN MODE IDCIN DROPS TO 20mA CHRG STATE: Hi-Z DCIN POWER REMOVED USBIN POWER REMOVED OR DCIN POWER APPLIED EN DRIVEN HIGH EN DRIVEN HIGH SHUTDOWN MODE IUSBIN DROPS TO 18mA CHRG STATE: Hi-Z
4075 F01
EN DRIVEN LOW
Figure 1. LTC4077 State Diagram of a Charge Cycle
4077f
11
LTC4077 APPLICATIO S I FOR ATIO
Thermal Limiting An internal thermal feedback loop reduces the programmed charge current if the die temperature attempts to rise above a preset value of approximately 105C. This feature protects the LTC4077 from excessive temperature and allows the user to push the limits of the power handling capability of a given circuit board without risk of damaging the device. The charge current can be set according to typical (not worst-case) ambient temperature with the assurance that the charger will automatically reduce the current in worstcase conditions. DFN power considerations are discussed further in the Applications Information section. Using a Single Charge Current Program Resistor In applications where the programmed wall adapter charge current and USB charge current are the same, a single program resistor can be used to set both charge currents. Figure 2 shows a charger circuit that uses one
100mA (USB, HPWR = LOW) 500mA WALL ADAPTER USB POWER LTC4077 DCIN USBIN 1mF 1mF HPWR GND RIUSBL 4.02k 1% RIUSB 2k 1% IUSBL IUSB GND PWR CHRG IDC RIDC 1.24k 1%
4077 F03
WALL ADAPTER USB PORT 1mF
LTC4077 DCIN USBIN 1mF IUSB IUSBL RISET 2k 1% IDC BAT HPWR
Figure 2. Dual Input Charger Circuit. The Wall Adapter Charge Current and USB Charge Currents (HPWR = High) are Both Programmed to be 500mA. If USBIN is the Supply and HPWR = Low, the Charge Current is 100mA
12
U
charge current program resistor. In this circuit, one registor programs the same charge current for each input supply (with HPWR = HIGH). ICHRG(DC) = ICHRG(USB) = 1000 V RISET The programmed charge current for USB supply with HPWR in its low state is: ICHRG(USBL) = 200 V RISET The LTC4077 can also program the wall adapter charge current and USB charge current independently using two program resistors, RIDC and RIUSB. Figure 3 shows a charger circuit that sets the wall adapter charge current to 800mA and the USB charge current to 500mA (HPWR = high) or 50mA (HPWR = low).
800mA (WALL) 500mA (USB, HPWR = HIGH) 50mA (USB, HPWR = LOW) BAT 1k 1k 4.2V 1-CELL Li-Ion BATTERY
W
U
U
+
+
4077 F02
Figure 3. Full Featured Dual Input Charger Circuit
4077f
LTC4077 APPLICATIO S I FOR ATIO
Stability Considerations The constant-voltage mode feedback loop is stable without any compensation provided a battery is connected to the charger output. However, a 1F capacitor with a 1 series resistor is recommended at the BAT pin to keep the ripple voltage low when the battery is disconnected. When the charger is in constant-current mode, the charge current program pin (IDC, IUSB or IUSBL) is in the feedback loop, not the battery. The constant-current mode stability is affected by the impedance at the charge current program pin. With no additional capacitance on this pin, the charger is stable with program resistor values as high as 20k; however, additional capacitance on these nodes reduces the maximum allowed program resistor. Power Dissipation When designing the battery charger circuit, it is not necessary to design for worst-case power dissipation scenarios because the LTC4077 automatically reduces the charge current during high power conditions. The conditions that cause the LTC4077 to reduce charge current through thermal feedback can be approximated by considering the power dissipated in the IC. Most of the power dissipation is generated from the internal MOSFET pass device, thus, the power dissipation is calculated to be: PD = (VIN - VBAT) * IBAT PD is the power dissipated, VIN is the input supply voltage (either DCIN or USBIN), VBAT is the battery voltage and IBAT is the charge current. The approximate ambient temperature at which the thermal feedback begins to protect the IC is: TA = 105C - PD * JA TA = 105C - (VIN - VBAT) * IBAT * JA
U
Example: An LTC4077 operating from a 5V wall adapter (on the DCIN input) is programmed to supply 800mA full-scale current to a discharged Li-Ion battery with a voltage of 3.3V. Assuming JA is 40C/W (see Thermal Considerations), the ambient temperature at which the LTC4077 will begin to reduce the charge current is approximately: TA = 105C - (5V - 3.3V) * (800mA) * 40C/W TA = 105C - 1.36W * 40C/W = 105C - 54.4C TA = 50.6C The LTC4077 can be used above 50.6C ambient, but the charge current will be reduced from 800mA. The approximate current at a given ambient temperature can be approximated by: IBAT = 105C TA ( VIN VBAT ) * qJA Using the previous example with an ambient temperature of 60C, the charge current will be reduced to approximately: IBAT = 105C 60C 45C = (5 V 3.3 V ) * 40C / W 68C /A IBAT = 662mA It is important to remember that LTC4077 applications do not need to be designed for worst-case thermal conditions, since the IC will automatically reduce power dissipation when the junction temperature reaches approximately 105C.
4077f
W
U
U
13
LTC4077 APPLICATIO S I FOR ATIO
Thermal Considerations In order to deliver maximum charge current under all conditions, it is critical that the exposed metal pad on the backside of the LTC4077 package is properly soldered to the PC board ground. When correctly soldered to a 2500mm2 double sided 1oz copper board, the LTC4077 has a thermal resistance of approximately 40C/W. Failure to make thermal contact between the exposed pad on the backside of the package and the copper board will result in thermal resistances far greater than 40C/W. As an example, a correctly soldered LTC4077 can deliver over 800mA to a battery from a 5V supply at room temperature. Without a good backside thermal connection, this number would drop to much less than 500mA. Protecting the USB Pin and Wall Adapter Input from Overvoltage Transients Caution must be exercised when using ceramic capacitors to bypass the USBIN pin or the wall adapter inputs. High voltage transients can be generated when the USB or wall
DRAIN-BULK DIODE OF FET WALL ADAPTER LTC4077 DCIN
4077 F04
Figure 4. Low Loss Input Reverse Polarity Protection
14
U
adapter is hot plugged. When power is supplied via the USB bus or wall adapter, the cable inductance along with the self resonant and high Q characteristics of ceramic capacitors can cause substantial ringing which could exceed the maximum voltage ratings and damage the LTC4077. Refer to Linear Technology Application Note 88, entitled "Ceramic Input Capacitors Can Cause Overvoltage Transients" for a detailed discussion of this problem. Always use an oscilloscope to check the voltage waveforms at the USBIN and DCIN pins during USB and wall adapter hot-plug events to ensure that overvoltage transients have been adequately removed. Reverse Polarity Input Voltage Protection In some applications, protection from reverse polarity voltage on the input supply pins is desired. If the supply voltage is high enough, a series blocking diode can be used. In other cases where the voltage drop must be kept low, a P-channel MOSFET can be used (as shown in Figure 4).
4077f
W
U
U
LTC4077 PACKAGE DESCRIPTIO U
DD Package 10-Lead Plastic DFN (3mm x 3mm)
(Reference LTC DWG # 05-08-1699)
0.675 0.05 PACKAGE OUTLINE 0.25 0.05 0.50 BSC 2.38 0.05 (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS R = 0.115 TYP 6 0.38 0.10 10 3.00 0.10 (4 SIDES) PIN 1 TOP MARK (SEE NOTE 6) 5 0.200 REF 0.75 0.05 2.38 0.10 (2 SIDES) BOTTOM VIEW--EXPOSED PAD NOTE: 1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WEED-2). CHECK THE LTC WEBSITE DATA SHEET FOR CURRENT STATUS OF VARIATION ASSIGNMENT 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE 1 1.65 0.10 (2 SIDES)
(DD10) DFN 1103
3.50 0.05 1.65 0.05 2.15 0.05 (2 SIDES)
0.25 0.05 0.50 BSC
0.00 - 0.05
4077f
Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
15
LTC4077 RELATED PARTS
PART NUMBER LTC3455 LTC4053 LTC4054/LTC4054X LTC4055 LTC4058/LTC4058X LTC4061 LTC4061-4.4 LTC4062 LTC4065/LTC4065A LTC4066 LTC4068/LTC4068X LTC4075 DESCRIPTION Dual DC/DC Converter with USB Power Management and Li-Ion Battery Charger USB Compatible Monolithic Li-Ion Battery Charger Standalone Linear Li-Ion Battery Charger with Integrated Pass Transistor in ThinSOT USB Power Controller and Battery Charger Standalone 950mA Lithium-Ion Charger in DFN Standalone Li-Ion Charger with Thermistor Interface Standalone Li-Ion Charger with Thermistor Interface Standalone Li-Ion Charger with Micropower Comparator Standalone 750mA Li-Ion Charger in 2mm x 2mm DFN USB Power Controller and Li-Ion Linear Battery Charger with Low-Loss Ideal Diode Standalone Linear Li-Ion Battery Charger with Programmable Termination Dual Input Standalone Li-Ion Battery Charger COMMENTS Efficiency >96%, Accurate USB Current Limiting (500mA/100mA), 4mm x 4mm QFN-24 Package Standalone Charger with Programmable Timer, Up to 1.25A Charge Current Thermal Regulation Prevents Overheating, C/10 Termination, C/10 Indicator, Up to 800mA Charge Current Charges Single-Cell Li-Ion Batteries Directly from USB Port, Thermal Regulation, 4mm x 4mm QFN-16 Package C/10 Charge Termination, Battery Kelvin Sensing, 7% Charge Accuracy 4.2V, 0.35% Float Voltage, Up to 1A Charge Current, 3mm x 3mm DFN-10 Package 4.4V, 0.4% Float Voltage, Up to 1A Charge Current, 3mm x 3mm DFN-10 Package 4.2V, 0.35% Float Voltage, Up to 1A Charge Current, 3mm x 3mm DFN-10 Package 4.2V, 0.6% Float Voltage, Up to 750mA Charge Current, 2mm x 2mm DFN-6 Package Seamless Transition Between Input Power Sources: Li-Ion Battery, USB and Wall Adapter, Low-Loss (50) Ideal Diode, 4mm x 4mm QFN-24 Package Charge Current up to 950mA, Thermal Regulation, 3mm x 3mm DFN-8 Package Charges Single-Cell Li-Ion Batteries from Wall Adapter and USB Inputs with Automatic Input Power Detection and Selection, 950mA Charger Current, Thermal Regulation, C/X Charge Termination, 3mm x 3mm DFN Package Charges Single-Cell Li-Ion Batteries from Wall Adapter and USB Inputs with Automatic Input Power Detection and Selection, 950mA Charger Current, Thermal Regulation, C/X Charge Termination, 3mm x 3mm DFN Package Manages Total Power Between a USB Peripheral and Battery Charger, Ultralow Battery Drain: 1A, ThinSOTTM Package Automatic Switching Between DC Sources, Load Sharing, Replaces ORing Diodes
LTC4076
Dual Input Standalone Li-Ion Battery Charger
LTC4410 LTC4411/LTC4412
USB Power Manager and Battery Charger Low Loss PowerPathTM Controller in ThinSOT
ThinSOT and PowerPath are trademarks of Linear Technology Corporation.
4077f
16 Linear Technology Corporation
(408) 432-1900
LT/LWI/TP 0705 500 * PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
FAX: (408) 434-0507 www.linear.com
(c) LINEAR TECHNOLOGY CORPORATION 2005

▲Up To Search▲

Price & Availability of LTC4077

	To Download LTC4077 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .